the link between voltage, current and resistance Ohm's Law

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Science coursework

Before conducting this experiment I found the link between voltage, current and resistance Ohm's Law. V=I x r

Resistance occurs when the electrons travelling along the wire collides with the atoms of the wire. These collisions slow down the flow of electrons causing resistance. Resistance is a measure of how hard it is to move the electrons through the wire.

I have decided to choose a factor that will affect the resistance of a wire.
I shall do this by going through all of the factors that affect the resistance of a wire and how I would measure each factor to find out which would be the most effective and easiest factor to measure. Below is a list of factors and reasons why they affect the resistance of a wire. From this list of factors I shall pick one factor to investigate.

 

Factors
1.Temperature: If the wire is heated up the atoms in the wire will start to vibrate because of their increase in energy. This results in more collisions between the electrons and the atoms as the atoms are moving into the electrons. This boost in collisions means that there will be an increase in resistance.
2. Material: The type of material will affect the number of free electrons which are able to flow through the wire. The number of electrons depends on the amount of electrons in the outer energy shell of the atoms, so if there are more or larger atoms then there must be more electrons available. If the material has a high number of atoms there will be high number of electrons causing a lower resistance because of the increase in the number of electrons. Also if the atoms in the material are closely packed then the electrons will have more frequent collisions and the resistance will increase.                                                                                                                      3. Wire length: If the length of the wire is increased then the resistance will also increase as the electrons will have a longer distance to travel and so more collisions will occur. Due to this the length increase should be proportional to the resistance increase.
4. Wire width: If the wires width is increased the resistance will decrease. This is because of the increase in the space for the electrons to travel through. Due to this increased space between the atoms there should be fewer collisions.

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The factor I have chosen is wire length the series of experiments I am about to do are used to examine the relation of the distance of the wire and the resistance.  

Apparatus:

· Power Pack

· Wire

· Leads

· Voltmeter

· Ammeter

Procedure

  1. take 5 different thickness of wires numbers 22 26 28 30 and 32
  2. Take a power pack, the connection wires, an ammeter and a voltmeter.
  3. connect up the red or black wire to the power pack and meters then position ...

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